By: Jason Carter, Summer Research Assistant, OMAFRA and Sean Westerveld, Ginseng and Herbs Specialist, OMAFRA
There are many different lavender (Lavandula angustifolia) and lavandin (L. x intermedia) cultivars that can be grown in Ontario. When choosing which cultivars to grow, lavender growers do not always consider (or have access to) the potential oil yield of the cultivars. Instead, they think of overall flower characteristics more than yield.
An experiment was conducted at the Simcoe Research Station to test the flower and oil yields from 34 different Angustifolia cultivars and 5 different lavandin cultivars. The trial was not replicated and was very small-scale, so the results can only be considered estimates. Flower bundles were collected from approximately 1 plant per cultivar for determination of dry weight of flowers destined for bundles. A separate harvest was conducted on another plant for oil extraction, which involved harvesting a smaller amount of stem material. Using a small glass distiller to extract the oil from 4-year-old plants, 250 grams of flower heads including some stem was collected from each cultivar. The extraction of oil began July 14th and finished August 2nd, taking 30 minutes of run time to extract the oil from each cultivar. Note: there is some variation in age of plants and the amount of winterkill among cultivars, so flower yield comparisons are less accurate than the oil yield comparison.
The dried flower and essential oil yields of each cultivar are presented in table 1. Our results show that the highest flower yield per plant of the angustifolia cultivars were ‘Melissa’, ‘Melissa Lilac’, and ‘Purple Bouquet’. The lowest flower yield per plant of the angustifolia cultivars were ‘Ellagance Snow’, ‘Arctic Snow’, and ‘Pink Perfume’. The highest flower yield per plant of the Lavandins was ‘Impress Purple’, and the lowest flower yield per plant was ‘Grosso’.
Table 1. Essential oil yield of lavender cultivars per 250 g of fresh flowers for 4-year-old plants (for most cultivars) grown at the Simcoe Research Station. For comparison, the dry weight of flowers per plant is provided as an estimate of flower yield, but was based on a longer stems than the harvest for oil extraction. Note: Variations in plant age and winter damage make flower yield less reliable as an indicator of cultivar performance.
Our results show that the highest oil yield per 250 g of flowers of the angustifolia cultivars were ‘Melissa’, ‘Ellagance Snow’, and ‘Sharon Roberts’. Note though that the ‘Sharon Roberts’ in this plot was determined to not match the original ‘Sharon Roberts’. The lowest yielding Angustifolia cultivars were ‘Folgate’ and ‘Pink Perfume’. Compared to the Angustifolia cultivars, the Lavandins produced a larger quantity of oil per weight of flowers. Our results show the highest yielding Lavandin cultivars were ‘Phenomenal’ and ‘Grosso’, and the lowest yielding was ‘Gros Bleu’.
It is important to consider both the flower yield per plant and the oil yield per weight of flowers to get a true picture of the oil yield of each cultivar. Although the flower yield in this study was based on dried bundles for which long stems are desirable, the yield comparison among cultivars provides a good approximation for determining the oil yield per plant. For example, ‘Ellagance Snow’ had a high oil yield per 250 g of flowers but had a very low flower yield per plant. This may not be the best choice when looking for a cultivar to increase oil yield. For angustifolia cultivars that have a high oil yield and high flower yield per plant, consider ‘Melissa’, ‘Melissa Lilac’, and ‘Sharon Roberts’. The Lavandin that had a high oil yield and high flower yield would be ‘Impress Purple’.
Further analysis of the data will be used to estimate flower and oil yield per hectare and identify cultivars suitable for all major purposes (e.g., bundles, buds, oil and aesthetics).